Generate TypeScript from JSON
Generate TypeScript types from JSON locally in the browser.
TypeScript interfaces will appear here...
Generate TypeScript Interfaces from JSON
Paste a JSON sample and turn it into TypeScript interfaces and type definitions without writing them by hand. The tool recursively processes nested objects and arrays to produce accurate type structures. It is useful for typing API response payloads, bootstrapping frontend data models, and quickly scaffolding types during prototyping.
Benefits: Instant interface generation from any valid JSON, recursive handling of nested objects and arrays, proper typing of strings, numbers, booleans, and null values, copy generated types to clipboard with one click, works entirely offline in your browser.
Best for: Typing REST API response payloads, bootstrapping frontend data models, rapid prototyping with real API data, replacing manual type writing during development, generating types from database query results, and onboarding to unfamiliar APIs by inspecting their response shapes.
Limitations and tradeoffs
- Generates a single root interface with inline types rather than separate named interfaces for nested objects
- Cannot infer optional fields or union types from a single JSON sample
- Empty arrays are typed as any[] since there is no element to infer the type from
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Browse Developer toolsQuestions before you use it
Does it handle nested objects and arrays?
Yes. The generator recursively processes nested objects and creates inline type definitions for each level. Arrays are typed based on the first element, so an array of objects produces a typed object array. Empty arrays are typed as any[] since there is no sample element to infer from.
Will it mark fields as optional?
Fields present in the JSON sample are typed as required. For optional fields, manually add a ? after the property name in the output. If you provide an array of objects with inconsistent keys, the generated interface will include all keys found across all objects as required.
What TypeScript version does the output target?
The generated interfaces are compatible with TypeScript 4.0+ and follow standard interface syntax. The output uses basic types like string, number, boolean, and null, which work across all modern TypeScript versions without any special compiler flags.
Can I customize the root interface name?
The default root interface is named "Root." You can rename it after copying the output to your project. For nested objects, the tool generates inline type definitions rather than separate named interfaces, so you may want to extract and name them manually for larger schemas.
How does it handle null values?
Null values in the JSON are typed as null in the TypeScript output. If a field could be either a string or null, you will need to manually adjust the type to string | null after generation, since the tool can only infer from the single sample value it sees.